Well cementing apparatus



Aug. 12, 1941. c. E. BURT WELL CEMENTING APPARATUS 3 SheerQs-Sheet 1 Filed Dec. 23, 1959 7 5 0 9 Y J ww w W I vim u v Erlh Afl/bi Ma 3 a 2 w. R a 9 M M/ f M; M C 7/ AA/ %A Ax; u

Aug. 12, 1941. c z. E. BURT WELL CEMENTING APPARATUS Filed Dec. 23, 1939 3 Sheets-Sheet 2 CLARENCE BURT,

Aug. 12, 1941,

c. E. BURT WELL CJEMEMTING APPARATUS Filed Dec. 23, 1939' 3 Sheets-Sheet 3 grwmwfom 62,4 RENCE if 5027,

Patented Aug. 12,1941

WELL CEMEN'lfING APPARATUS Clarence E. Burt, Los Angeles, Calif., assignor to Baker Oil Tools, Inc., Huntington a corporation of California 7 Park, CaliL, w

Application December 23, 1939, Serial No. 310,811

33 Claims. This invention relates to the cementing of 1 wells, and is particularly concerned with controlling the passage of cementitiousslurry and other fluids laterally through well casings.

In multiple stage cementing operation, only part of the required total of cement slurry is pumped through the lower end of the casing, the remainder being displaced laterally through the casing at one or more predetermined positions above its bottom. Certain devices employed in such operations include elements carried within the casing and operable by plugs passing downwardly through the casing for controlling lateral ports, through which the slurry is to be displaced. However, there is the ever present danger that a plug employed in the cementing of a lower stage might, in passing through an upper stage, prematurely open its ports and thus allow passage of the cement slurry intended for the lower stage through the upper part of the casing string. This situation quite obviously prevents the completion of the cementing operation in the manner intended.

Accordingly, it is an object of the present invention to control the various cementing passages in a casing string without the necessity for lowering plugs or the like through the casing, or for moving the casing from the surface of the bore.

It is a further object of the invention to pro the apparatus being capable of controlling the flow of fluids laterally through its cementing passages and of restricting the bore in the casing string to Prevent the movement of plugs or other vide a cementing apparatus for use as part of a casing string, having normally closed cementing passages capable of being opened by the direct application of fluid under pressure to parts of said apparatus, without the need for restricting the interior of the casing and for passing plugs or other objects therethrough.

Another object of the inventionis to provide a cementing apparatus forming part of a casing string having an unrestricted bore, the apparatus including lateral cementing passages initially held'closed by positive instrumentalities which are adapted'to be rendered inefiective by the direct application of hydraulic pressure to said apparatus, permitting the passages to be opened by means contained within the apparatus itself, and without the assistance of devices within the casing bore.

Still a further object of the invention is to control the cementing passages in adevice forming part of a casing string by the application of pressure to fluids externally of the casing string.

Yet another object of the invention is to provide a cementing apparatus forming part of a casing string having a normally unrestricted bore,

similar objects downwardly beyond the point at which the apparatus ispositioned, in order to enforce flow of cement slurry or other fluids through the cementing passages.

A further object of the invention is to provide an improved apparatus for controlling the passage of cementitious slurry or other fluids through a string of casing.

This invention has'other objects which will become apparent from a consideration of the various formsof apparatus shown in the drawings accompanying and forming part of the present specification. These forms will now be described in detail, but it is to be understood that such detailed description is not to be taken in a limited sense, since the scope of the invention is best defined by the claims appended hereto.

Referring to the drawings:

Fig. 1 is a longitudinal section, partly in elevation, of a control head connected to a casing string embodying the present invention;

Fig. 2 is a fragmentary, longitudinal section through one form of a valve controlled ported casing collar that can be employed in the system disclosed in Fig. 1;

Fig. 3 is a longitudinal section, partly in elevation, of the device shown in Fig. 2' with its valve parts in a different position of operation;

Fig. 4 is a transverse section, taken as indicated by the line 4-4 in Fig. 3;

Fig. 5 is a fragmentary, longitudinal section through another form of valve controlled ported casing collar;

Fig. 6 is a view similar to Fig. 5 with the parts illustrated in a different position of operation;

Fig 7 is a fragmentary, longitudinal section through still another embodiment of the inventhrough another modification of the invention;

In Fig. l, the apparatus A constituting part of the present invention is disclosed as forming an intermediate part of a casing string B, termiment of the bottom plug III will be prevented,

and the continued application of pressure to the fluid on the top plug II will move it downwardly, forcing the cement slurry ahead of it and past the bottom plug packing l2, through its passages l3 into and through the float shoe, from where The fluid required to trip the sleeve can be placed around the outside of the casing string B 1 and maintained therein under pressure by atit will travel upwardly around the casing B. As

soon as the top plug contacts the bottom plug, substantially the entire batch of cement will have been displaced through the shoe.

taching a suitable control head D to the surface or water string E adjacent the casing string. and providing a packing seal F on the head engaging the casing string to prevent fluid leakage upwardly thereof. The fluid can be forced downwardly around the casing string 13 through the pipe G entering the control head, passing through the outlet ports 24 for action upon the upper portion,

of the valve sleeve or piston 22. When pressure to a suflicient degree has been generated, the shear screws will be fractured and thepiston will move downwardly to uncover the inlet openings 23 and establish communication between them and the outlet openings 24 (see Fig. 3). An observer at the surface of the bore will know that this condition has been achieved either by noting a material drop in the fluid pressure or by getting returns from the interior of the cas- In order to avoid the necessity for cementing a long string of casing by forcing the entire required quantity of cement slurry outwardly through the casing shoe, a multiple stage cementing system is employed. In this system, only suflicient slurry is displaced through the shoe to ing B.

After having been moved downwardly clear of the inlet ports, the valve sleeve 22 will be pre- 25. vented from reverting to its initial position by a cement the casing part way of its length, further displacement of cement to the exterior of the casing occurring through lateral passages provided in an upper stage collar A.

The present invention contemplates a cementing collar having passages-for the flow of fluid that are normally and positively closed, but

whose opening can be effected through the direct ably integral with the lower female threaded portion, and having its upper end threaded in the upper female collar portion Ii. Circumscribing l9 welded to the upper and lower female members in spaced relationship to the bottom 20 of an extended circumferential recess on the exterior of the inner body I8, to define an annular cylinder or chamber 2|, in which an annular sleeve valve or piston 22 is slidable to control inlet ports or openings 23 provided in the inner body and fluid outlet ports or openings 24 provided in the upper female collar portion l6. In the instant case, the latter ports are constituted by circumferentially spaced longitudinal slots extending through the upper collar portion.

The slidable valve sleeve or piston 22 is initially positioned across the inlet ports 23 to prevent itscommunication with the outlet ports 24, and is positively held in this position by one or more shear screws 25, or other frangible devices, threaded through the outer body l9 into the valve sleeve 22. Leakage of fluid past the sleeve is prevented -by annular hydraulic packings 26, 21 provided at its upper and lower ends.

Movement of the sleeve or piston valve 22 is this inner body member is an outer body portion determined by conducting fluid under sufficient pressure to either of its ends to shear the frangible screws 25, whereupon the sleeve can be moved to a position rendering the inlet ports 23 communicative with the outlet ports 24.

split, annular contractile lock ring 28 normally carried in an internal recess 29 in the outer body member 19 and engageable in a mating groove 30 in the exterior of the sleeve, which aligns with it upon downward movement of the sleeve. It will be noted that the contacting bottom surfaces 3l, 32 of the contractile ring and mating groove are disposed substantially at right angles to the direction of movement of the sleeve to insure that its return movement-does not occur, and that the inner face 33 of the ring is inclined downwardly and inwardly so as to be displaced into its recess upon its engagement by the lower end of the sleeve 22.

In some cases, premature tripping of the sleeve size and number as to withstand a greater shear-.

ing force, and are preferably fractured by pressure applied from within the casing, the fluid under pressure moving through one or more lower inlet ports 34 into the annular cylinder 2| for action upon the lower hydraulic packing 21 and piston to shear the screws and force the annular piston upwardly. Movement in. this latter direction is limited by an abutment or stop 35 provided by the lower end of the upper female collar portion l6. Thereafter, the pressure in side of the casing can be relieved and the fluid reversely circulated in the manner aforementioned to move the sleeve valve downwardly until its upper end 26 clears the inlet ports 23. Under these conditions, very little pressure is necessary to move the sleeve since it is operating against substantially no resistance, other than that due to friction. In view of the very low and minor external pressure required, the formation not subjected to detrimental high pressures which might cause its breakdown and loss of fluid.

During cenznting of the lower stage, the sleeve valve 22 is held in position across the inlet ports 23 by the shear screws 25 to prevent loss of fluid through the upper stage collar A.- After the bottom stage has been cemented, reverse flow of the cementitious slurry through the shoe C is prevented by engagement of the back pressure ball 36 with its seat 31, and further passage of fluid downwardly through the shoe'is prevented by the sleeve 22 downwardly clear of the inlet portsunder the impetus of the reversely circulated fluid.

With the inlet ports open, a predetermined quantity of cement slurry at the surface of the bore is placed on top of the mud within the easing and pumped down the casing, displacing the 1 mud ahead of it through the inlet ports or 1 openings 23 and out through the outlet ports 24 for upward passage toward the surface of the bore. The cement slurry is followed by a measured quantity of mud, which is sufficient to insure that substantially all of the cement slurry will be caused to pass through the ports in the stage collar. After the batch of cement has thus been properly placed, its reverse flow into the casing can be prevented by closing the casinginlet at the surface until the cement has set, after which the inlet can be opened, without danger of the slurry flowing back into the casing through the open passages 23, 24.

Comingling of the mud and cement columns can be prevented by placing the cement slurry within the casing between upper and lower plugs, and pumping these plugs with the intervening cement downwardly in a manner similar to that described in connection with the cementing of the lower stage. As soon as the lower plug has passed the inlet ports 23, it will no longer be urged downwardly due to the flow of the cement slurry through the lateral passages, which relieves the pressure on the lower plug, and also because of the inability of the fluid column below the inlet ports to be displaced. However, the upper plug will continue to move downwardly forcing the cement slurry through the inlet and outlet ports 23, 24 into theannular space between the casing and sides of the hole. Whenthe upper plug contacts the lower one, the required amount of slurry will have been displaced laterally through the casing.

In some instances, it may be desirable to lower a bridging plug through the casing to offer assurance that the mud column preceding the batch of cement slurry will pass outwardly through the casing. As shown in Figure 3, one form of bridge plug that can be employed includes a body member 39 having radial ribs 40 extending throughout the greater portion of its length, and carrying a cup-shaped packing M at its lower end clamped in position between the body of. the'plug and a terminal plate d2 threaded-onto a pin 43 extending from the body.

This plug is pumped downwardly through the casing, but as soon as the packing M passes the inlet ports 23, its further motion will be arrested due to the loss of pressure incident to flow of the pumped fluid through the inlet and outlet passages. By remaining in position below the inlet openings, the plug serves as a bridging element, preventing the passage of fluids downwardly through the casing below the inlet ports of the cementing collar.

A modified form of cementing collar is disclosed in Figures 5 and 6. The screws 25 holding the sleeve 22 across the inlet ports can be sheared by fluid under pressure passing through the lower inlet ports M, as described in connection with Figures 2 to 4. However, it is not necessary to reverse circulation to move the sleeve screws releases this'spring and permits its exi pansion for the purpose of moving the slidable sleeve downwardly to its fullest extent (see Fig. 6). Fluids can now pass laterally through this stage of the casing, flowing from the inlet port 23, through intermediate openings 45 provided through the sleeve, and through outlet ports 46 in the outer body member H! ,of the cementing collar.

Should the spring 44 fall to move the sleeve 22 to open position, pressure can be applied to the fluid externally of the casing, which will pass through ports 41 at the upper portion of the outer body member and act upon the upper end of the piston valve 22 to shift it downwardly to open position. However, such reverse circulation will normally not be required, being provided primarily as an additional-device for shiftingthe sleeve in its conflningcylinder or chamber 2!.

The bridging plug 39-43 disclosed in Figure 3 comes to rest below the inlet ports 23 solely because the casing fluid above it can pass laterally through the collar. The embodiments of the invention shown in Figures 7 to 11, inclusive. provide a positive arrangement of parts for .arresting downward travel of the bridge plug, without restricting the internal bore of the easing until after cementing operations through a lower stage have been completed.

The general arrangement of parts disclosed in Figures 7 to 10, inclusive, is the same as that shown in Figures 5 and 6. A split expansible ring 48 is positioned within a recess 49 formed in the inner face of the inner body member Hi below the inlet ports 23. Secured to or abutting this split ring are a plurality of buttons 50 extending through elongated openings 5| in the inner body member and into circumferentially ,a position wholly confined within its recess 49,

leaving the bore of the casing string unrestricted through the stage cementing collar. Upon tripping of the sleeve valve 22, either by passage of fluid under pressure through the lower port '34 or through the ports 24- or 41, described above, the spring 44 will move the sleeve valve 22 downwardly to open position and at the same time move the fingers 53 in the same'direction within their confining grooves 52, causing their inclined faces 54 to ride over the outer ends of the buttons 50 and press them inwardly to position the expansible ring 48 partly within the bore of the casing string (seeFig. 8). The engagement of the contractile latch ring 28 with the groove 30,

4- agcnevv its further downward movement and causes it to function as a bridging element. The fluid and cement slurry now moved down the casing, either with or without the use of upper and lower cement confining plugs, must pass outwardly through the passages 23, 45, 46.

The arrangement shown in Figure 11 is substantially the same as that disclosed in Figures 7 to 10, except that fluid must be reversely circulated, as in Figure 2, to slide the sleeve valve 22 and the fingers 53 below it downwardly after the shear screws 25 have been disrupted. The bridge plug 55 will cooperate with the elements of this modification in the same manner as was described in connection with Figures '7 to 10, downward movement of the plug being positively arrested by the expansible spring ring 48.

The various modifications exemplifying the present invention offer assurance that the ports in the upper stage collars A will remain closed until desired to be opened. The collar valve mechanisms do not require elements within the casing bore for their.operation,which might be prematurely operated by the passage therethrough of plugs employed in cementing a lower stage. Instead of utilizing positive mechanical means for opening the valve ports, applicant applies fluid under pressure directly to parts of his stage collar, which parts are not positioned within the casing string. Instead, they occupy confined positions, oflering protection against premature tripping and assurance that multiple stage cementing operations can follow the procedure outlined.

While the valve sleeve and other parts have been disclosed as arranged to open the passages upon downward movement, it is apparent that the parts could be so positioned as to allow lateral passage through the casing upon upward movement of the piston valve 22 to the required extent.

I claim: I I

1. A cementing device comprising a tubular member having one or more openings therethrough and adapted to form part of a casing string, a valve member on the exterior of said tubular member for controlling flow of fluid through said openings, and frangible means for positively maintaining said valve member in position to prevent passage of fluid through said openings, said frangible means being disruptable hydraulically to permit movement of said valve member to a position allowing flow of fluid through said openings.

2. A cementing device comprising a tubular member adapted to form part of a casing string andhaving an unrestricted central bore and one or more openings therethrough, .a valve member on the exterior of said tubular member for controlling flow of fluidthrough said openings, and frangible means for positively maintaining said valve means in position to prevent passage of fluid through said openings, said frangible means being disruptable by fluid under a predetermined pressure to permit movement of said valve member to a position allowing flow of fluid through said openings.

3. A cementing device comprising a tubular member having one or more lateral openings therethrough and adapted to form part of a casing string, a sleeve valve member on the exterior of said tubular member for controlling flow of fluid through said openings, and frangible means for positively maintaining said sleeve valve member in position to prevent passage of fluid 7 ing string, a cylinder on said tubular member,' valve means in said cylinder for controlling flow.

through said openings, said frangible means being disruptable hydraulically to permit sliding of said sleeve valve member toa position allowing flow of fluid through said openings.

4. A cementing device member adapted to form part of. a casing strin and having an unrestricted central bore and one or more lateral openings therethrough, a sleeve valve member on the exterior of said tubular member for controlling flow of fluid through said openings, and frangible means for positively maintaining said sleeve valve in position to prevent passage of fluid through said openings, said frangible means being disruptable by fluid under a predetermined pressure to permit sliding of said sleeve valve member to a position allowing flow of fluid through said openings.

5. A cementing device comprising a tubular member having one or more lateral openings therethrough and adapted to form part of a string of easing, a cylinder on the exterior of said tubular member, valve means within said cylinder for controlling flow of fluids through said openings, positive locking means normally retaining said valve means in position to prevent passage of fluid through said openings, and means for conducting fluid to said cylinder to render said locking means ineflective, to permit movement of said valve means to a position allowing flow of fluid through said openings.

6. A cementing device comprising a tubular member having one or more lateral openings therethrough and adapted to form part of a casing string, a cylinder on said tubular member, valve means in said cylinder for controlling fiow of fluids through said openings, means normally 7. A cementing device comprising a tubular' member having one or more lateral openings therethrough and adapted to form part of a casing string, a cylinder on said tubular member, valve means in said cylinder for controlling flow of fluids through said one or more openings, means normally retaining said valve means in position to prevent passage of fluids through said one or more openings, means for moving said valve means in one direction to render said retaining means ineffective, and means for moving saidvalve means in another direction to permit flow of fluids through said one or more openings.

8. A cementing device comprising a tubular member having one or more lateral openings therethrough and adapted to form part of a casing string, a cylinder on saidtubular member, valve means in said cylinder for controlling flow of fluids through said one or more openings, and means for preventing said valve means from allowing flow of fluids through said one or more openings in response to fluid pressure within said tubular member.

9. A cementing device comprising a tubular member having one or more lateral openings therethrough and adapted to form part of a casof fluids through said one or more openings, means for preventing said valve means from alcomprising a tubular' lowing flow of fluids through said one or more openings in response to fluid pressure within said tubular member, and means externally of said tubular member whereby said valve means is movable to a position permitting flow of fluids through said one or more openings. 10. A cementing device comprising a member having a lateral opening therethrough and adapted to form part of a casing string, a second member spaced from said member and forming a fluid chamber therewith, piston valve means slidable within said chamber for selectively preventing or permitting flow of fluids through said opening, means for conducting motivating fluid to said chamber to slidesaid piston valve means therein and determine its selective operating position with respect to said opening, and means for preventing said valve means from allowing flow of fluids through said opening in response to fluid pressure within said member. ,7

11. A cementing device adapted to connect casing sections together in spaced relation, said device having an annular cylinder, means providing inlet and outlet passages through said device communicative with said cylinder, an annular valve member slidable in said cylinder to control the flow of fluid through said passages, and means for preventing said valve means from allowing interior andexterior of the device, a piston valve slidable in said chamber and normally preventing passage of fluid between said openings, means for conducting fluid to said chamber from the exterior of said outer member to enable said piston valve to shift in said chamber to a position allowing passage of fluid between said openings.

13. A cementing device comprising inner and outer body members defining a chamber therebetween, said members having communicable openings for the passage of fluid between the interior and exterior of the device, a piston valve slidable in said chamber and normally preventing passage of fluid between said openings, means for conducting fluid to said chamber to enable said piston valve to shift therein to a position allowing passage of fluid between said openings, and means for retaining said piston valve in said last-mentioned position.

14. A cementing device comprising inner and outer body members defining a chamber therebetween, said members having communicable openings for the passage of fluid between the interior and exterior of the device, a piston valve slidable in said chamber, frangible means normally retaining said piston valve in position outer body members defining a chamber therebetween, said members having respective inlet'and outlet openings communicable with said chamber, a piston valve slidable in said chamber and normally positioned across said inlet opening, said outlet opening being adapted to conduct fluid under pressure from the exterior of said device to said chamber for action on said piston valve and eflect its movement to a position freeing said inlet opening and allowing fluid passage between said inlet and outlet openings.

16. A cementing device comprising inner and outer body members defining a chamber therebetween, said members having respective inlet and outlet openings communicable with said chamber, a piston valve slidable in said chamber and normally positioned across said inlet opening, said outlet opening being adapted to conduct fluidunder pressure from the exterior of said device to said chamber for action on said piston valve to effect its-movement to a position freeing said inlet opening and allowing fluid passage between said inlet and outlet openings, and means for retaining said piston valve in said last-mentioned position.

1'7. A cementing device comprising inner and outer body members defining a chamber therebetween, said members having respective inlet and outlet openings communicable with said chamber, a piston valve slidable in said chamber, frangible means normally retaining said piston valve across said inlet opening, said outlet opening'being adapted to conduct fluid under pressure from the exterior of said device to said chamber for action on said piston valve to disrupt said frangible means and move said piston valve to a position freeing said inlet opening and allowing fluid passage between said inlet and outlet openings.

18. A cementing device adapted to form part of a casing string, comprising inner and outer body members defining a chamber therebetween, said members having respective inlet and outlet openings communicable with said chamber, a double acting piston valve slidable in said chamber and normally positioned across said inlet opening, said outlet opening being adapted to conduct fluid under pressure from the exterior of said device to said chamber for action on one end of said piston valve to slide it to a position free of said inlet opening, frangible means normally retaining said piston valve across said inlet opening, said inner body having a second inlet opening communicable with said chamber to conduct fluid under pressure therein to the other end of said piston valve to disrupt said frangible means.

19. A cementing device adapted to form part of a casing string, comprising inner and outer body members defining a chamber therebetween, said members having respective inlet and outlet openings communicable with said chamber, a piston valve slidable in said chamber and normally positioned therein to prevent passage of fluid I between said openings, said inner body having a second inlet opening communicable with said chamber to conduct fluid into said chamber, whereby said piston valve may be shifted to a position allowing passage of fluid between said first mentioned inlet and outlet openings.

20. A cementing device adapted to form part of a casing string, comprising inner and outer body members defining a chamber therebetween, said members having respective inlet and outlet openings communicable with said chamber, a piston valve slidable in said chamber, frangible means normally retaining said piston valve in position to prevent passage of fluid between said v openings, said inner body member having a sec- 0nd inlet opening communicable with said cham-' her to conduct fluid thereinto for action upon said piston valve to disrupt said frangible means and allowing movement of said piston valve to a position in which flow oi fluid between said first mentioned inlet and outlet openings can occur.

21. A cementing device adapted to form part of a casing string, comprising inner and outer body members defining a'chamber therebetween, said members having respective inlet and outlet openings communicable with said chamber, a piston valve slidable in said chamber, spring means tending to move said piston valve in one direction within said chamber to a position permitting flow of fluids between said openings, and means for conducting fluid into said chamber to move said piston valve in another direction.

22. A cementing device adapted to form part of a casing string, comprising inner and outer body members defining a chamber therebetween, said members having respective inlet and outlet openings communicable with said chamber, a piston valve slidable in said chamber, and spring means tending to move said piston valve in said chamber to a position permitting flow of fluid between said openings.

23. A cementing device comprising a tubular member having a lateral opening therethrough and adapted to form part 01' a casing string, a cylinder on said tubular member, valve means in said cylinder for controlling flow of fluids through said openings. and spring means tending to move said valve means in said cylinder to a position permitting flow of fluid through said opening.

24. A cementing device adapted to form part of a casing string, comprising inner and outer body members defining a chamber therebetween, said members having respective inlet and outlet openings communicable with said chamber, a piston valve slidable in said chamber, means normally retaining saidpiston valve inposition to prevent passage of fiuid between said openings, spring means tending to move said piston valve within said chamber to a position permitting flow of fluid between said openings, and means for conducting fluid into said chamber to render said retaining means ineffective and permit movement of said piston valve by said spring means.

25. A cementing device adapted'to form part of a casing string, comprising inner and outer body members defining a chamber therebetween, said members having respective inlet and outlet openings communicable with said chamber, a

and having a central longitudinal bore, means carried by said tubular means initially in retracted position clear 01 its bore, and means re- 28. A cementing device comprising tubular means adapted to form part of a casing string and having a central longitudinal bore, means carried by said tubular means initially in resaid members having respective inlet and outlet tracted position with respect to its bore, and means movable with respect to said retracted means for projecting the latter into said bore to enable it to arrest a device adapted to be sent down said casing string.

29. A cementing device comprising tubular means adapted to form part of a casing string and having a central longitudinal bore and a lateral passage establishing communication between the interior and exterior of said device, a slide valve for controlling th flow of fluid through said passage, and means movable laterally into said bore upon shifting of said slide valve with respect to said passage, said lastmentioned means being operable to arrest passage of a cementing plug sent down said casing string.

30. A cementing device adapted to form part of a casing'string, comprising inner and outer body members defining a chamber therebetween, said members having respective inlet and outlet openings communicable with said chamber, a piston valve slidable in said chamber and normally preventing passage of fluid between said openings, means enabling said piston valv to be shifted in said chamber to a position allowing passage of fluid between saidopenings, and means movable into the inner bore of said inner body member in response to such shifting movement of said piston valve.

31. A cementing device adapted to form part of a casing string comprising inner and outer body members defining a chamber therebetween,

. openings communicable with said chamber, a

piston valve slidable in said chamber, frangible means normally retaining said piston valve across said inlet opening to prevent passage of fluid between the interior and exterior of said device, spring means operative on one end of said piston valve to move the latter to a position free of said inlet opening, and means for conducting fluid under pressure into said chamber for action on the other end of said piston valve to disrupt said frangible means and permit movement of said piston valve underv the influence of said spring means.

26. A cementing device adapted to form part of a casing string and having a lateral passage device adapted to be sent down said casing string.

27;, A cementing devicecomprising tub'ular means adapted to form part of a casing string piston valve slidable in said chamber and normally preventing passage of fluid between said openings, means enabling said piston valve to be shifted in said chamber to a position allowing passage'oi fluid between said openings,

plug arresting means initially contained within the inner body member without restricting the interior of the bore of said casing string, and 'cam means movable by said piston valve for positioning said plug arresting means into said bore to restrict the same.

32. A cementing device as defined in claim 31, said plug arresting means comprising an expansiblering contained within an inner recess in the inner body member, and said cam means comprises one or more fingers engageable with said piston valve, and each having a cam surface engageable with a button cooperable with said expansible ring.

33. A cementing device adapted to form part of a casing string comprising inner and outer body members defining an annular cylinder therebetween, said members having respective inlet and outlet openings communicating with said cylinder, an annular piston slidable within said cylinder and normally positioned across said inlet opening to prevent passage of fluid between said openings, hydraulic means enabling said annular piston to be shifted in said cylinder to open said inlet opening, an expansible ring contained within a recess in the interior oi the inner body member and below said inlet openwardly from said expansible ringinto said grooves for engagement by said inclined surfaces to move the expansible ring into the bore of the cementing device upon downward movement of 5 said annular piston.

CLARENCE E. BURT. 

